Various conventional bearings are known, including sliding bearings, ball bearings, and roller bearings. The roller bearings can be further divided into cylindrical roller bearings, tapered roller bearings, needle bearings, and barrel roller bearings. A conventional tapered roller bearing comprises an inner ring having a roller bearing axis, an outer ring which is disposed around the inner ring, a cage between the inner ring and the outer ring, and a plurality of rolling elements retained in the cage between the outer ring and the inner ring. In tapered roller bearings, the rolling elements are conical and are aligned such that their rotational axes are inclined relative to the rotational axis of the bearing axis, that is, the rotational axes of the conical rolling elements are not parallel to the rotational axis of the bearing. Further, in tapered roller bearings, the cage has a small lateral ring or edge, a large lateral ring or edge and a plurality of bridges or crosspieces that extend from the small lateral ring to the large lateral ring and which are spaced in the circumferential direction.
Rotating the inner ring relative to the outer ring causes the conical rolling elements to rotate about their axes and revolve around the bearing axis. The rolling elements are spaced from one another in the circumferential direction by the crosspieces of the cage, and the rolling elements roll on both the inner ring and on the outer ring. To avoid or reduce friction, in particular rolling friction and/or sliding friction between the rolling elements and the outer ring or the inner ring as well as relative to the cage, a lubricant is conventionally applied to various contact surfaces of the bearing.
A conventional cage for a tapered roller bearing has an inclined (relative to the bearing axis) or oblique arrangement of crosspieces that extend between the rolling elements or rollers, in accordance with the conically formed raceways, and the tapered rollers which are inclined relative to the bearing axis. During operation of tapered rollers, it has been observed that only a limited amount of grease or lubricant can be retained on the cage crosspieces. This is because, during operation, the grease or lubricant tends to be pumped by centrifugal force to the large edge or lateral ring of the cage which has a greater diameter than the small edge or lateral ring of the cage. Due to this unwanted pumping of lubricant out to the large edge of the cage, the lubricant is not available on the crosspieces in sufficient quantity to perform a principal function of the lubricant, namely to lubricate the rollers, and the cage does not adequately dispense the lubricant onto the outer surface of the rollers. Therefore, in conventional tapered roller bearings, this function can not always be performed satisfactorily or completely.
Conventional efforts to address this problem involve using greater quantities of grease or other lubricant. However, this disadvantageously leads to increased lubricant churning, and it is generally desirable to reduce lubricant churning. It has been found to be difficult to achieve adequate lubrication without unduly increasing lubricant churning.